Rotary dredge cutter-head having spaced guard members

ABSTRACT

Cutter-head for use in a dredging system for dredging sand and gravel which has a plurality of spaced guard members extending from the trailing edge of each support member toward an adjacent support member but spaced therefrom. The guard members are located inward of cutting teeth coupled to the leading edge of each support member. The guard members block the passage of large rocks into the interior of the head but to allow the passage of roots and clay along with the sought after sand and gravel thereby preventing the roots and clay from blocking the openings of the cutter-head.

llnited States Patent [1 1 Hamm ROTARY DREDGE CUTTER-HEAD HAVING SPACEDGUARD MEMBERS [451 Sept. 25, 1973 Primary Examiner-Edgar S. BurrAssistant Examiner-Clifford D. Crowder AttorneyWm. T. Wofford et a1.

[5 7 ABSTRACT Cutter-head for use in a dredging system for dredging sandand gravel which has a plurality of spaced guard members extending fromthe trailing edge of each support member toward an adjacent supportmember but spaced therefrom. The guard members are located inward ofcutting teeth coupled to the leading edge of each support member. Theguard members block the passage of large rocks into the interior of thehead but to allow the passage of roots and clay along with the soughtafter sand and gravel thereby preventing the roots and clay fromblocking the openings of the cutterhead.

12 Claims, 4 Drawing Figures ROTARY DREDGE CUTTER-HEAD HAVING SPACEI)GUARD MEMBERS BACKGROUND OF THE INVENTION This invention relates to animproved cutter-head for use in a dredging system to allow moreefficient dredging operations to be carried out in old sand and gravelpits.

In the processing of sand and gravel for commercial purposes, stripmining operations have been carried out in the past to select and removeonly the best grade of material. These operations have resulted in largeamounts of desirable sand and gravel still remaining in the pits. Due tothe methods employed originally in the strip mining operations, the sandand gravel remaining in these old pits are mixed with other soils anddebri such as clay and roots. Hence selective mining operations nowcannot be carried out to remove only the sought after sand and gravel.From a practical standpoint, if these old pits are to be reclaimed, allof the material must be removed.

In my operations, I use a dredge equipped with a rotating cutter-head toremove the material from the pits. The cutter-head includes a pluralityof spaced support members curving outward from a forward central hub andbackward to an annular shaped frame. Outwardly extending cutting meanswhich may be spaced teeth are coupled to the leading edge of eachsupport member. A shaft extends through the annular shaped frame and iscoupled to the interior side of the hub for. rotating the head in agiven direction to allow the teeth to carry out their cutting operation.The sand and gravel and other material loosened by the cutter-head ispumped through the head to the dredge by way of a conduit and pumplocated on the dredge. From the dredge, the material is conveyed ortransported to a sand and gravel washing plant.

Heretofore difficulties were experienced in the dredging operations inthat large rocks would either pass through the head to the pump or belodged between the openings of the head which would require a shut-downoperation in order to remove or dislodge the rocks. An attempt was madeto remedy the situation by welding spaced guards or rods to adjacentsupport members and which completely bridged the opening betweenadjacent support members. These guards did block the passage of largerrocks however they contributed to the problem in that roots would becometangled around these bridging guards which would result in the openingsbecoming blocked especially when loose clay and soil would build up orcollect on the entangled roots. When this occurred the entirecutter-head would become a solid mass of clay and roots therebyrequiring shut-down operations to remove the clay and roots from thecutter-head.

SUMMARY OF THE INVENTION In accordance with the present invention, thereis provided a cutter-head for a dredging system which eliminates theabove mentioned problems. The cutterhead includes a plurality of spacedsupport members curving outward from a forward central hub andbackmember. These guard members have trailing ends which extend towardan adjacent or following support member but are spaced therefrom andfrom its cutting means. The outer extremities of each guard member arespaced substantially inward from the circle of revolution made by theclosest cutting edge of the cutting means coupled to the adjacentsupport member. The top surfaces of the trailing edges of the supportmembers also are free and clear of the guard members.

In the embodiment disclosed, a plurality of spaced teeth are coupled tothe leading edge of each support member and extend outward and away fromthe axis of the shaft. The guard members are coupled to the trailingedges of the support members and the trailing ends of the guard membersare located substantially inward of the cutting edges of the closestteeth coupled to the following support members. With this arrangementthe guard members will block the passage of the larger rocks but allowthe passage of sand and gravel as well as the passage of clay and rootsinto the interior of the cutter-head. Due to the arrangement andposition of the guard members, roots will slide off of the. guardmembers and into the interior of the head as it rotates rather thanbecoming entangled around the guard members.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 illustrates a dredge equippedwith a rotary cutter-head for carrying out dredging operations;

FIG. 2 is a rear-side view of the cutter-head of the present invention;

FIG. 3 is a cross-section of FIG. 2 taken through a plane extendingperpendicular to the axis of the shaft looking toward the front end ofthe cutter-head and illustrating the rearmost guard members of acutterhead; and

FIG. 4 is a front-side view of the cutter-head of the present invention.

DETAIL DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1,there is illustrated a barge ll floating on a body of water 13 andequipped with a rotary cutter-head 15 for removing sand, gravel andother material from the body or earth formation 17 which may form partof an old sand and gravel pit.

Referring to FIGS. 2-4, the cutter-head comprises a plurality of spacedsupport members 21, 23, 25, 27, 29, and 31 curving outward from aforward central hub 33 and spiraling backward to an annular shaped framemember 35. A shaft 37 extends through the annular shaped frame and iscoupled to the interior side of the hub 33 for rotating the head in agiven direction to allow the head to carry out its cutting operations.In FIG. 3, the direction of rotation is counterclockwise as illustratedby the arrow 39. Each support member has a leading edge to which aplurality of spaced teeth are coupled for cutting and dislodging thematerial. Referring to the support member 21, the leading edge isidentified by reference character 21A while its trailing edge isidentified by reference character 21B. Teeth 41, 43, 45, 47, and 49 areillustrated as being coupled to the leading edge of the support member21. They are welded to the leading edge in such a manner that theyextend outward from the axis of the shaft. In a given planeperpendicular to the axis of shaft 37, for example, as illustrated inFIG. 3, the distance from the axis of the shaft 37 to leading edge 21Aof support member 21 is greater than the distance from the axis of theshaft 37 to the trailing edge 218. The other support members and theirteeth have the same relationship.

The cutter-head is rotated by way of shaft 37 and a rotary driveillustrated at 51 on the barge. Extending to the lower portion of theinterior of the cutter-head and below the shaft 37 is a suction tube 53which has its other end extending to a suction pump 55 located on thebarge.

In operation, the cutter-head is lowered or raised by the hoistarrangement illustrated at 57 while it is rotated and while the suctionpump 55 is operating. As the cutter-head rotates, the teeth of the headcut and loosen the material. The loosened material falls or is forced inbetween the support members through the openings, for example asillustrated at 61 and 63, and into the interior of the cutter-head wherethe material is impelled or drawn into the conduit 53 by way of thesuction force. The material then is conveyed by way of the tube 53 ontothe barge and from the pump 55 conveyed to a gravel washing plant by wayof another conduit not shown. The barge may be rotated to differentpositions around a pivot axis 65 extending from the barge and imbeddedin the earth.

The cutter-head employed is a commercially available cutter-head whichhas been modified to solve the problem presented by large rocks, rootsand clay present in the pits.

As indicated previously large rocks tended to become caught in theopenings of the cutter-head or else were forced through the openingswhere they became lodged in the pump. Attempts to remedy the situationwere made by welding elongated rods or guards completely across theopenings and to adjacent support members to bridge the openings. Thiscaused roots to become tangled around the bridging guards and whichprovided a mass upon which clay would collect and completely clog orblock the openings of the cutterhead.

The situation was solved by modifying the cutterhead by welding to eachsupport member at its trailing end and on the underside thereofaplurality of spaced guard members which extend toward an adjacentsupport member but spaced therefrom. In the embodiment disclosed, threeguard members welded to the trailing edge of each support member werefound to be sufficient to solve the problem. In FIG. 2, the three guardmembers welded to the trailing edge of support member 21, are identifiedby reference characters 71, 73, and 75. In FIG. 3, only the rearmostguard members are illustrated. Referring to the guard membersillustrated in FIG. 3, it can be seen that their outer extremities arespaced substantially inward from the tips of the cutting teeth.Moreover, each guard member generally follows the same contour of itssupport member in a direction transverse to the shaft axis. The trailingend of each guard member extends to a point nearly below the tip of theclosest following tooth relative to the shaft axis. In addition, thetrailing end of each guard member is spaced from the leading edge of theadjacent or following support member. The other guard members locatedtoward the forward hub also have the same relative relationship. Inaddition, the top surfaces of the support members at their trailingedges also are free and clear of protruding structure. Thus, as thecutter-head rotates, sand and gravel and other material such as rootsand clay are allowed to pass below the teeth through the openings andthrough the spaces between the guard members and into the interior ofthe cutter-head. The guard members, however will block the passage ofthe larger rocks. Since the guard members on a given support memberextend away from the direction of rotation of the support member and arespaced from the adjacent support member and its teeth, roots will slideoff of the guard members as the head rotates and pass into the interiorof the cutter-head rather than becoming entangled around the guardmembers. Thus a mass of roots will not be able to collect on thecutter-head thereby eliminating the collection of clay on the roots andhence on the cutter-head which would otherwise block the openings of thecutter-head.

Instead of six support members, as illustrated in FIGS. 2-4, thecutter-head may have five support members. In the following example,dimensions will be given for a cutter-head having five equally spacedsupport members rather than six. In this example, reference will be madeto support members 21 and 23 and guard member 71 shown in FIG. 3, butwith the assumption that these members are part of the cutter-headhaving five support members.

In the plane of FIG. 3, for a five support member head, the leading edgeof each support member is about 18 inches from the shaft axis, whiletheir trailing edges are about 16 inches from the shaft axis. In thishead, the tip of tooth 77 is about 23 inches from the shaft axis. Theleading end of guard member 71, where it is coupled to the trailing endof support member 21, is less than 16 inches from the shaft axis. Inaddition, the trailing edge 71A of guard member 71 is about 15 r inchesfrom the shaft axis. Thus the outer extremities of guard member 71 areabout 7 inches radially inward from the maximum radius of the tip oftooth 77. The trailing edge 71A and guard member 71 extends to a pointspaced about 7 or 8 inches from the leading edge of support member 23.In the plane of FIG. 3, for a five support member cutter-head, the otherguard members have the same relationship. In addition the other guardmembers toward the forward end of the head also have similarrelationships.

The frame 35 for the five support member cutterhead, has a maximumdiameter of about 42 inches and the head has a length of about 48inches. On a head having five support members, the support members atthe rear end of the head have a width of about 12 inches and taper to anarrower width toward the front of the cutter-head. The openings betweenadjacent support members also taper from a wide opening to a narroweropening going from the rear end to the forward end of the cutter-head.On the head having five support members, the openings at the rear end ofthe cutterhead between adjacent support members are about 15 inches fromsupport member to support member. For a head having five supportmembers, the guard members 71, 73, and 75 are spaced about 8 or 9 inchesapart and have lengths of about 9 inches, 7 inches, and 5 inchesrespectively. Guard member 71 is spaced about 10 inches from frame 35.

Since the lengths of the guard members of each support member decreaseprogressively towards the front end of the head, the distance betweenthe trailing ends of the three guard members of a given support memberand the adjacent or following support member remains about constant.This is also true with respect to the distance between their trailingends and the top cutting edge of the closet tooth of an adjacent orfollowing support member.

The cutter-head having five support members described above, may allowrocks up to 6 inches in diameter to pass through the head but will blockthe passage of larger rocks, for example those having diameters of 9,10, or 12 inches.

In operation, the cutter-head may be rotated at a speed of about 30revolutions per minute to carry out its cutting and dislodgementoperations.

Instead of spaced teeth, a continuous cutting blade may be coupled tothe leading edge of each support member. Each blade would have the samerelationship to the various components of the head as the set of teeththat it replaces. Blades instead of teeth may be employed when dredgingin softer material.

I claim: I

1. A cutter-head for a dredging system comprising:

a plurality of spaced support members curving outward from a forwardcentral hub and backward to an annular shaped frame,

said members each having a leading edge and a trailing edge,

cutting means coupled to the leading edge of each support member,

said cutting means having cutting edges for carrying out cuttingoperations,

a shaft extending through said annular shaped frame and coupled to theinterior side of said hub for rotating the head in a given direction toallow said cutting means to carry out their cutting operations, and

a plurality of spaced guard members coupled to each support memberand'having trailing ends extending toward a following support member butspaced therefrom and from its cutting means,

the outer extremities of each guard member being spaced substantiallyinward from the circle of revolution made by the closest cutting edge ofsaid cutting means coupled to the following support member,

each extending guard member generally following the same contour of itssupport member transverse to the shaft axis.

2. The cutter-head of claim 1 wherein:

' said cutting means coupled to each support member extend outward andaway from the axis of said shaft.

3. The cutter-head of claim 2 wherein:

said cutting means comprises a plurality of spaced teeth coupled to theleading edge of each support member, and extendingoutward and away fromthe axis of said shaft,

the trailing ends of each guard member being located inward of thecutting edge of the closest tooth coupled to an adjacent followingsupport member.

4. The cutter-head of claim 2 wherein:

said guard members are connected to the trailing edges of said supportmembers.

5. The cutter-head of claim 4 wherein:

said guard members are connected to the underside of said supportmembers.

6. The cutter-head of claim 4 wherein:

the top surfaces of said support members at their trailing edges have asmooth and continuous surface from said hub to said frame.

7. The cutter-head of claim 4 wherein:

said guard members are connected only to the trailing edges of saidsupport members.

8. The cutter-head of claim 4 wherein:

the top surfaces of said support members are free and clear of saidguard members.

9. The cutter-head of claim 1, wherein said cutterhead is for use indredging sand and gravel mixed with clay, roots, and large rocks,

the outer extremities of each guard member being spaced inward aboutone-third of the radius of the circle of revolution made by the closestcutting edge of said cutting means coupled to the following supportmember.

10. The cutter-head of claim 9, wherein:

each guard member, in a plane transverse to the axis of said shaft andextending through the guard member and through the support member towhich it is coupled, has its outer extremities spaced inward from theouter extremities of its support member.

11. A cutter-head for a dredging system comprising:

a plurality of spaced support members curving outward from a forwardcentral hub and backward to an annular shaped frame,

said members each having a leading edge and a trailing edge,

cutting means coupled to the leading edge of each support member,

said cutting means having cutting edges for carrying out cuttingoperations,

a shaft extending through said annular shaped frame and coupled to theinterior side of said hub for rotating the head in a given direction toallow said cutting means to carry out their cutting operations,

and

plurality of spaced guard members coupled to the trailing edge of eachsupport member and having trailing ends extending toward an adjacentsupport member but spaced therefrom and from its cutting means,

the outer extremities of each guard member being located at a distancefrom the axis of said shaft less than the distance from said axis of theclosest cutting edge of said cutting means coupled to an adjacentfollowing support member,

the leading edges of said support members being further from the axis ofsaid shaft than their trailing edges,

the top surfaces of said suport members being free and clear of saidguard members.

12. A cutter-head for a dredging system for use in dredging sand andgravel mixed with clay, roots, and large rocks, comprising:

a plurality of spaced support members curving outward from a forwardcentral hub and backward to an annular shaped frame,

said members each having a leading edge and a trailing edge,

cutting means coupled to the leading edge of each support member, 7

said cutting means having cutting edges for carrying out cuttingoperations,

a shaft extending through said annular shaped frame and coupled to theinterior side of said hub for rotating the head in a given direction toallow said cutting means to carry out their cutting operations, and

than the distance from said axis of the closest cut ting edge of saidcutting means coupled to an adjacent following support member,

the leading edges of said support members being further from the axis ofsaid shaft than their trailing edges.

1. A cutter-head for a dredging system comprising: a plurality of spacedsupport members curving outward from a forward central hub and backwardto an annular shaped frame, said members each having a leading edge anda trailing edge, cutting means coupled to the leading edge of eachsupport member, said cutting means having cutting edges for carrying outcutting operations, a shaft extending through said annular shaped frameand coupled to the interior side of said hub for rotatiNg the head in agiven direction to allow said cutting means to carry out their cuttingoperations, and a plurality of spaced guard members coupled to eachsupport member and having trailing ends extending toward a followingsupport member but spaced therefrom and from its cutting means, theouter extremities of each guard member being spaced substantially inwardfrom the circle of revolution made by the closest cutting edge of saidcutting means coupled to the following support member, each extendingguard member generally following the same contour of its support membertransverse to the shaft axis.
 2. The cutter-head of claim 1 wherein:said cutting means coupled to each support member extend outward andaway from the axis of said shaft.
 3. The cutter-head of claim 2 wherein:said cutting means comprises a plurality of spaced teeth coupled to theleading edge of each support member, and extending outward and away fromthe axis of said shaft, the trailing ends of each guard member beinglocated inward of the cutting edge of the closest tooth coupled to anadjacent following support member.
 4. The cutter-head of claim 2wherein: said guard members are connected to the trailing edges of saidsupport members.
 5. The cutter-head of claim 4 wherein: said guardmembers are connected to the underside of said support members.
 6. Thecutter-head of claim 4 wherein: the top surfaces of said support membersat their trailing edges have a smooth and continuous surface from saidhub to said frame.
 7. The cutter-head of claim 4 wherein: said guardmembers are connected only to the trailing edges of said supportmembers.
 8. The cutter-head of claim 4 wherein: the top surfaces of saidsupport members are free and clear of said guard members.
 9. Thecutter-head of claim 1, wherein said cutter-head is for use in dredgingsand and gravel mixed with clay, roots, and large rocks, the outerextremities of each guard member being spaced inward about one-third ofthe radius of the circle of revolution made by the closest cutting edgeof said cutting means coupled to the following support member.
 10. Thecutter-head of claim 9, wherein: each guard member, in a planetransverse to the axis of said shaft and extending through the guardmember and through the support member to which it is coupled, has itsouter extremities spaced inward from the outer extremities of itssupport member.
 11. A cutter-head for a dredging system comprising: aplurality of spaced support members curving outward from a forwardcentral hub and backward to an annular shaped frame, said members eachhaving a leading edge and a trailing edge, cutting means coupled to theleading edge of each support member, said cutting means having cuttingedges for carrying out cutting operations, a shaft extending throughsaid annular shaped frame and coupled to the interior side of said hubfor rotating the head in a given direction to allow said cutting meansto carry out their cutting operations, and a plurality of spaced guardmembers coupled to the trailing edge of each support member and havingtrailing ends extending toward an adjacent support member but spacedtherefrom and from its cutting means, the outer extremities of eachguard member being located at a distance from the axis of said shaftless than the distance from said axis of the closest cutting edge ofsaid cutting means coupled to an adjacent following support member, theleading edges of said support members being further from the axis ofsaid shaft than their trailing edges, the top surfaces of said suportmembers being free and clear of said guard members.
 12. A cutter-headfor a dredging system for use in dredging sand and gravel mixed withclay, roots, and large rocks, comprising: a plurality of spaced supportmembers curving outward from a forward central hub and backward to anannular shaped frame, said memBers each having a leading edge and atrailing edge, cutting means coupled to the leading edge of each supportmember, said cutting means having cutting edges for carrying out cuttingoperations, a shaft extending through said annular shaped frame andcoupled to the interior side of said hub for rotating the head in agiven direction to allow said cutting means to carry out their cuttingoperations, and a plurality of spaced guard members connected only tothe trailing edge of each support member and having trailing endsextending toward an adjacent support member but spaced therefrom andfrom its cutting means, the outer extremities of each guard member beinglocated at a distance from the axis of said shaft less than the distancefrom said axis of the closest cutting edge of said cutting means coupledto an adjacent following support member, the leading edges of saidsupport members being further from the axis of said shaft than theirtrailing edges.